The U.S. Has Quietly Made Some Remarkable Advances in Fuel-Efficiency

In 1975, largely in response to OPEC's oil embargo against the United States, Congress enacted a new energy law that included provisions to increase "Corporate Average Fuel Economy." These CAFE standards, as they're known, led to a remarkable jump in the fuel efficiency for the U.S. auto fleet, with a near doubling of fuel economy and a 50 percent jump for light trucks in just a decade. But federal policymakers coddled the auto industry in the 1970s, and by the 1980s the fuel-efficiency curve had plateaued.

Then, in 2008, oil prices went really crazy—breaking the unheard-of level of $140 per barrel. In the run-up, a Democratic Congress passed and President Bush signed into law the historic Energy Independence and Security Act of 2007, which required the fleetwide CAFE standard be increased to at least 35 miles per gallon by 2020. The Environmental Protection Agency and the U.S. Department of Transportation developed new standards for emissions and fuel economy, issuing a series of landmark rules culminating in the 2012 requirement that the standard ramp up to 54.5 mpg by 2025.